When we think of tech infrastructure, we think of our fiber optic cables, electric meters, and tons of wires that our Internet Service Providers (ISPs) and others keep adding on. In some cases, those eyesores are hanging from poles along our roads, and in others, it is neatly tucked underground, but in either case, we don’t know how good or bad they are unless there is an outage. While my motive today is to talk about fixing tech infrastructure we can’t see, it’s more to do with a set of satellites – GPS satellites!
Global Positioning Systems or GPS is something we all use regularly either from our smartphones or other smart devices. They help us navigate from one place to the other and help us track our food delivery or cab down to the very intersection it is currently at. A total of 32 satellites were launched starting from 1978, with 24 of them operational at any point in time to assist ground-based operations. Initially limited to the US military, unrestricted civilian access started in 2000 and the uses have been infinite so far. All autonomous moving equipment, smartphones, data centers, etc. rely on the use of GPS signals.
How Does It Work?
Ancient sailors used the constellations in the sky to identify where they were and where they were heading to. Today, we have replaced stars with satellites that are floating around 20000 km above the Earth’s surface and completing two complete revolutions around the Earth per day. Each of the satellites is equipped with an atomic clock that sends out the current time on the satellite. Your receiver/device picks up the signal from 4 such satellites to compute its actual location. While it is possible to compute this information with 3 such satellites, the 4th satellite simply helps you eliminate the need for an accurate atomic clock on your device.
Still, confused? Try this explanation from Reddit user u/nalc.
Imagine if you were somewhere near 3 cities. You don’t know where you are, but each city is sending out a signal, and from this signal, you can determine exactly how far you are from the city, but not where you are or from which direction it is coming.
If you figure out that you’re a distance of x from City A, you know that you are somewhere on a circle of radius x centered at City A, but you don’t know which direction you are. If you figure out that you’re a distance of y from City B, and draw another circle of radius y centered at City B, this will intersect your first circle at two locations, so now you know that you are somewhere around one of those two locations, but not which one. If you figure out that you’re distance of z from City C, and draw a circle of radius z around City C, you’ll find that this intersects the first two circles at one point. That point, where all 3 circles intersect, is your exact position.
In addition to just navigation of cars and airplanes, these timestamps are also used to ensure timestamps & delivery of transactions to cloud data centers, etc. Now that you know how it works, you must be thinking about how it supports so many devices at one time when it was launched in the 70s. The good part is that your device can do all the calculations and navigational heavy lifting and all the satellite must do is broadcast the time onboard. While this sounds very simplistic, GPS has had its fair share of issues too so far. Since the signal strength is so weak, it doesn’t work as expected indoors or when you’re close to too many buildings. Bad weather also leads to lowered accuracy and often miscalculated locations. Finally, such a simplistic system is often susceptible to foul play like someone spoofing a time signal or blocking GPS signals (South Korea Claims that North Korea frequently Jams their GPS Signals). Car thieves in some countries are known to employ cheap GPS jammers to prevent owners from tracking the whereabouts of their stolen cars.
With the criticality of these systems to both military and civilian personnel, upgrades are required to ensure that all messages are encrypted so nobody can block or misguide you by affecting your signal. Additionally, it is also about the time that we have stronger signals that can penetrate buildings and support indoor maps (so I can finally return to where I parked my car at the mall) even if it is raining outside. The National Defense Authorization Act of 2021 has asked the US Armed Forces to come up with a working prototype for a new and improved GPS resiliency plan by 2023. 2023 doesn’t seem all that far out, so in the meantime let me know what else you would want from a new and improved GPS in the comments.
Fount of wisdom, insufferable know it all, make it go away are just some of the phrases used to define Melwyn. When he is not at his Consulting job, he spends his time reading about technology and current affairs.